CGAL 5.3  3D Triangulations

#include <CGAL/Triangulation_3.h>
Inherited by CGAL::Regular_triangulation_3< Traits, TDS, SLDS >.
The class Triangulation_3
represents a 3dimensional tetrahedralization of points.
Traits  is the geometric traits class and must be a model of TriangulationTraits_3 . 
TDS  is the triangulation data structure and must be a model of TriangulationDataStructure_3 . Default may be used, with default type Triangulation_data_structure_3<Triangulation_vertex_base_3<Traits>, Triangulation_cell_base_3<Traits> > . Any custom type can be used instead of Triangulation_vertex_base_3 and Triangulation_cell_base_3 , provided that they are models of the concepts TriangulationVertexBase_3 and TriangulationCellBase_3 , respectively. 
SLDS  is an optional parameter to specify the type of the spatial lock data structure. It must be a model of the SurjectiveLockDataStructure concept, with Object being a Point (as defined below). It is only used if the triangulation data structure used is concurrencysafe (i.e. when TriangulationDataStructure_3::Concurrency_tag is Parallel_tag ). The default value is Spatial_lock_grid_3<Tag_priority_blocking> if the triangulation data structure is concurrencysafe, and void otherwise. In order to use concurrent operations, the user must provide a reference to a SLDS instance via the constructor or Triangulation_3::set_lock_data_structure . 
Traversal of the Triangulation
The triangulation class provides several iterators and circulators that allow one to traverse it (completely or partially).
Public Types  
enum  Locate_type { VERTEX =0, EDGE, FACET, CELL, OUTSIDE_CONVEX_HULL, OUTSIDE_AFFINE_HULL } 
The enum Locate_type is defined by Triangulation_3 to specify which case occurs when locating a point in the triangulation. More...  
Types  
The class  
typedef Traits  Geom_traits 
typedef TDS  Triangulation_data_structure 
typedef SLDS  Lock_data_structure 
typedef Triangulation_data_structure::Vertex::Point  Point 
typedef Geom_traits::Segment_3  Segment 
typedef Geom_traits::Triangle_3  Triangle 
typedef Geom_traits::Tetrahedron_3  Tetrahedron 
Only vertices (0faces) and cells (3faces) are stored. Edges (1faces) and facets (2faces) are not explicitly represented and thus there are no corresponding classes (see Section Representation).  
typedef Triangulation_data_structure::Vertex  Vertex 
typedef Triangulation_data_structure::Cell  Cell 
typedef Triangulation_data_structure::Facet  Facet 
typedef Triangulation_data_structure::Edge  Edge 
typedef Triangulation_data_structure::Concurrency_tag  Concurrency_tag 
Concurrency tag (from the TDS).  
The vertices and faces of the triangulations are accessed through A handle is a model of the  
typedef Triangulation_data_structure::Vertex_handle  Vertex_handle 
handle to a vertex  
typedef Triangulation_data_structure::Cell_handle  Cell_handle 
handle to a cell  
typedef Triangulation_simplex_3< Self >  Simplex 
Reference to a simplex (vertex, edge, facet or cell) of the triangulation.  
typedef Triangulation_data_structure::size_type  size_type 
Size type (an unsigned integral type)  
typedef Triangulation_data_structure::difference_type  difference_type 
Difference type (a signed integral type)  
typedef Triangulation_data_structure::Cell_iterator  All_cells_iterator 
iterator over cells  
typedef Triangulation_data_structure::Facet_iterator  All_facets_iterator 
iterator over facets  
typedef Triangulation_data_structure::Edge_iterator  All_edges_iterator 
iterator over edges  
typedef Triangulation_data_structure::Vertex_iterator  All_vertices_iterator 
iterator over vertices  
typedef unspecified_type  Finite_cells_iterator 
iterator over finite cells  
typedef unspecified_type  Finite_facets_iterator 
iterator over finite facets  
typedef unspecified_type  Finite_edges_iterator 
iterator over finite edges  
typedef unspecified_type  Finite_vertices_iterator 
iterator over finite vertices  
typedef unspecified_type  Point_iterator 
iterator over the points corresponding to the finite vertices of the triangulation.  
typedef Triangulation_data_structure::Cell_circulator  Cell_circulator 
circulator over all cells incident to a given edge  
typedef Triangulation_data_structure::Facet_circulator  Facet_circulator 
circulator over all facets incident to a given edge  
typedef unspecified_type  Segment_cell_iterator 
iterator over cells intersected by a line segment. More...  
typedef unspecified_type  Segment_simplex_iterator 
iterator over simplices intersected by a line segment. More...  
In order to write C++ 11  
typedef Iterator_range< unspecified_type >  All_cell_handles 
range type for iterating over all cell handles (including infinite cells), with a nested type iterator that has as value type Cell_handle .  
typedef Iterator_range< All_facets_iterator >  All_facets 
range type for iterating over facets.  
typedef Iterator_range< All_edges_iterator >  All_edges 
range type for iterating over edges.  
typedef Iterator_range< unspecified_type >  All_vertex_handles 
range type for iterating over all vertex handles, with a nested type iterator that has as value type Vertex_handle .  
typedef Iterator_range< unspecified_type >  Finite_cell_handles 
range type for iterating over finite cell handles, with a nested type iterator that has as value type Cell_handle .  
typedef Iterator_range< Finite_facets_iterator >  Finite_facets 
range type for iterating over finite facets.  
typedef Iterator_range< Finite_edges_iterator >  Finite_edges 
range type for iterating over finite edges.  
typedef Iterator_range< unspecified_type >  Finite_vertex_handles 
range type for iterating over finite vertex handles, with a nested type iterator that has as value type Vertex_handle .  
typedef Iterator_range< unspecified_type >  Points 
range type for iterating over the points of the finite vertices.  
typedef Iterator_range< unspecified_type >  Segment_traverser_cell_handles 
range type for iterating over the cells intersected by a line segment.  
typedef Iterator_range< Segment_simplex_iterator >  Segment_traverser_simplices 
range type for iterating over the simplices intersected by a line segment.  
Creation  
Triangulation_3 (const Geom_traits &traits=Geom_traits(), Lock_data_structure *lock_ds=nullptr)  
Introduces a triangulation t having only one vertex which is the infinite vertex. More...  
Triangulation_3 (Lock_data_structure *lock_ds=nullptr, const Geom_traits &traits=Geom_traits())  
Same as the previous one, but with parameters in reverse order.  
Triangulation_3 (const Triangulation_3 &tr)  
Copy constructor. More...  
template<class InputIterator >  
Triangulation_3 (InputIterator first, InputIterator last, const Geom_traits &traits=Geom_traits(), Lock_data_structure *lock_ds=nullptr)  
Equivalent to constructing an empty triangulation with the optional traits class argument and calling insert(first,last) .  
Assignment  
Triangulation_3 &  operator= (const Triangulation_3 &tr) 
The triangulation tr is duplicated, and modifying the copy after the duplication does not modify the original. More...  
void  swap (Triangulation_3 &tr) 
The triangulations tr and t are swapped. More...  
void  clear () 
Deletes all finite vertices and all cells of t .  
template<class GT , class Tds1 , class Tds2 >  
bool  operator== (const Triangulation_3< GT, Tds1 > &t1, const Triangulation_3< GT, Tds2 > &t2) 
Equality operator. More...  
template<class GT , class Tds1 , class Tds2 >  
bool  operator!= (const Triangulation_3< GT, Tds1 > &t1, const Triangulation_3< GT, Tds2 > &t2) 
The opposite of operator== .  
Access Functions  
const Geom_traits &  geom_traits () const 
Returns a const reference to the geometric traits object.  
const Triangulation_data_structure &  tds () const 
Returns a const reference to the triangulation data structure.  
Triangulation_data_structure &  tds () 
Returns a reference to the triangulation data structure. More...  
int  dimension () const 
Returns the dimension of the affine hull.  
size_type  number_of_vertices () const 
Returns the number of finite vertices.  
size_type  number_of_cells () const 
Returns the number of cells or 0 if t.dimension() < 3 .  
Vertex_handle  infinite_vertex () 
Returns the infinite vertex.  
void  set_infinite_vertex (Vertex_handle v) 
This is an advanced function. More...  
Cell_handle  infinite_cell () const 
Returns a cell incident to the infinite vertex.  
NonConstantTime Access Functions  
As previously said, the triangulation is a collection of cells that are either infinite or represent a finite tetrahedra, where an infinite cell is a cell incident to the infinite vertex. Similarly we call an edge (resp. facet)  
size_type  number_of_facets () const 
The number of facets. More...  
size_type  number_of_edges () const 
The number of edges. More...  
size_type  number_of_finite_cells () const 
The number of finite cells. More...  
size_type  number_of_finite_facets () const 
The number of finite facets. More...  
size_type  number_of_finite_edges () const 
The number of finite edges. More...  
Geometric Access Functions  
Tetrahedron  tetrahedron (Cell_handle c) const 
Returns the tetrahedron formed by the four vertices of c . More...  
Triangle  triangle (Cell_handle c, int i) const 
Returns the triangle formed by the three vertices of facet (c,i) . More...  
Triangle  triangle (const Facet &f) const 
Same as the previous method for facet f . More...  
Segment  segment (const Edge &e) const 
Returns the line segment formed by the vertices of e . More...  
Segment  segment (Cell_handle c, int i, int j) const 
Same as the previous method for edge (c,i,j) . More...  
const Point &  point (Cell_handle c, int i) const 
Returns the point given by vertex i of cell c . More...  
const Point &  point (Vertex_handle v) const 
Same as the previous method for vertex v . More...  
Tests for Finite and Infinite Vertices and Faces  
bool  is_infinite (Vertex_handle v) const 
true , iff vertex v is the infinite vertex.  
bool  is_infinite (Cell_handle c) const 
true , iff c is incident to the infinite vertex. More...  
bool  is_infinite (Cell_handle c, int i) const 
true , iff the facet i of cell c is incident to the infinite vertex. More...  
bool  is_infinite (const Facet &f) const 
true iff facet f is incident to the infinite vertex. More...  
bool  is_infinite (Cell_handle c, int i, int j) const 
true , iff the edge (i,j) of cell c is incident to the infinite vertex. More...  
bool  is_infinite (const Edge &e) const 
true iff edge e is incident to the infinite vertex. More...  
Queries  
bool  is_vertex (const Point &p, Vertex_handle &v) const 
Tests whether p is a vertex of t by locating p in the triangulation. More...  
bool  is_vertex (Vertex_handle v) const 
Tests whether v is a vertex of t .  
bool  is_edge (Vertex_handle u, Vertex_handle v, Cell_handle &c, int &i, int &j) const 
Tests whether (u,v) is an edge of t . More...  
bool  is_facet (Vertex_handle u, Vertex_handle v, Vertex_handle w, Cell_handle &c, int &i, int &j, int &k) const 
Tests whether (u,v,w) is a facet of t . More...  
bool  is_cell (Cell_handle c) const 
Tests whether c is a cell of t .  
bool  is_cell (Vertex_handle u, Vertex_handle v, Vertex_handle w, Vertex_handle x, Cell_handle &c, int &i, int &j, int &k, int &l) const 
Tests whether (u,v,w,x) is a cell of t . More...  
bool  is_cell (Vertex_handle u, Vertex_handle v, Vertex_handle w, Vertex_handle x, Cell_handle &c) const 
Tests whether (u,v,w,x) is a cell of t and computes this cell c . More...  
There is a method The analogous methods for facets are defined here.  
bool  has_vertex (const Facet &f, Vertex_handle v, int &j) const 
If v is a vertex of f , then j is the index of v in the cell f.first , and the method returns true . More...  
bool  has_vertex (Cell_handle c, int i, Vertex_handle v, int &j) const 
Same for facet (c,i) . More...  
bool  has_vertex (const Facet &f, Vertex_handle v) const 
bool  has_vertex (Cell_handle c, int i, Vertex_handle v) const 
Same as the first two methods, but these two methods do not return the index of the vertex.  
The following three methods test whether two facets have the same vertices.  
bool  are_equal (Cell_handle c, int i, Cell_handle n, int j) const 
bool  are_equal (const Facet &f, const Facet &g) const 
bool  are_equal (const Facet &f, Cell_handle n, int j) const 
For these three methods: More...  
Point Location  
The class It provides also functions to test if a given point is inside a finite face or not. Note that the class  
Cell_handle  locate (const Point &query, Cell_handle start=Cell_handle(), bool *could_lock_zone=nullptr) const 
If the point query lies inside the convex hull of the points, the cell that contains the query in its interior is returned. More...  
Cell_handle  locate (const Point &query, Vertex_handle hint, bool *could_lock_zone=nullptr) const 
Same as above but uses hint as the starting place for the search.  
Cell_handle  inexact_locate (const Point &query, Cell_handle start=Cell_handle()) const 
Same as locate() but uses inexact predicates. More...  
Cell_handle  locate (const Point &query, Locate_type <, int &li, int &lj, Cell_handle start=Cell_handle(), bool *could_lock_zone=nullptr) const 
If query lies inside the affine hull of the points, the \( k\)face (finite or infinite) that contains query in its interior is returned, by means of the cell returned together with lt , which is set to the locate type of the query (VERTEX, EDGE, FACET, CELL , or OUTSIDE_CONVEX_HULL if the cell is infinite and query lies strictly in it) and two indices li and lj that specify the \( k\)face of the cell containing query . More...  
Cell_handle  locate (const Point &query, Locate_type <, int &li, int &lj, Vertex_handle hint, bool *could_lock_zone=nullptr) const 
Same as above but uses hint as the starting place for the search.  
Bounded_side  side_of_cell (const Point &p, Cell_handle c, Locate_type <, int &li, int &lj) const 
Returns a value indicating on which side of the oriented boundary of c the point p lies. More...  
Bounded_side  side_of_facet (const Point &p, const Facet &f, Locate_type <, int &li, int &lj) const 
Returns a value indicating on which side of the oriented boundary of f the point p lies: More...  
Bounded_side  side_of_facet (const Point &p, Cell_handle c, Locate_type <, int &li, int &lj) const 
Same as the previous method for the facet (c,3) .  
Bounded_side  side_of_edge (const Point &p, const Edge &e, Locate_type <, int &li) const 
Returns a value indicating on which side of the oriented boundary of e the point p lies: More...  
Bounded_side  side_of_edge (const Point &p, Cell_handle c, Locate_type <, int &li) const 
Same as the previous method for edge \( (c,0,1)\).  
Flips  
Two kinds of flips exist for a threedimensional triangulation. They are reciprocal. To be flipped, an edge must be incident to three tetrahedra. During the flip, these three tetrahedra disappear and two tetrahedra appear. Figure 45.1 (left) shows the edge that is flipped as bold dashed, and one of its three incident facets is shaded. On the right, the facet shared by the two new tetrahedra is shaded. Flips are possible only under the following conditions:  the edge or facet to be flipped is not on the boundary of the convex hull of the triangulation  the five points involved are in convex position. The following methods guarantee the validity of the resulting 3D triangulation. Flips for a 2d triangulation are not implemented yet.  
bool  flip (Edge e) 
bool  flip (Cell_handle c, int i, int j) 
Before flipping, these methods check that edge e=(c,i,j) is flippable (which is quite expensive). More...  
void  flip_flippable (Edge e) 
void  flip_flippable (Cell_handle c, int i, int j) 
Should be preferred to the previous methods when the edge is known to be flippable. More...  
bool  flip (Facet f) 
bool  flip (Cell_handle c, int i) 
Before flipping, these methods check that facet f=(c,i) is flippable (which is quite expensive). More...  
void  flip_flippable (Facet f) 
void  flip_flippable (Cell_handle c, int i) 
Should be preferred to the previous methods when the facet is known to be flippable. More...  
Insertions  
The following operations are guaranteed to lead to a valid triangulation when they are applied on a valid triangulation.  
Vertex_handle  insert (const Point &p, Cell_handle start=Cell_handle()) 
Inserts the point p in the triangulation and returns the corresponding vertex. More...  
Vertex_handle  insert (const Point &p, Vertex_handle hint) 
Same as above but uses hint as the starting place for the search.  
Vertex_handle  insert (const Point &p, Locate_type lt, Cell_handle loc, int li, int lj) 
Inserts the point p in the triangulation and returns the corresponding vertex. More...  
template<class PointInputIterator >  
std::ptrdiff_t  insert (PointInputIterator first, PointInputIterator last) 
Inserts the points in the range [first,last) in the given order, and returns the number of inserted points.  
template<class PointWithInfoInputIterator >  
std::ptrdiff_t  insert (PointWithInfoInputIterator first, PointWithInfoInputIterator last) 
Inserts the points in the iterator range [first,last) in the given order, and returns the number of inserted points. More...  
We also provide some other methods that can be used instead of They are also guaranteed to lead to a valid triangulation when they are applied on a valid triangulation.  
Vertex_handle  insert_in_cell (const Point &p, Cell_handle c) 
Inserts the point p in the cell c . More...  
Vertex_handle  insert_in_facet (const Point &p, const Facet &f) 
Inserts the point p in the facet f . More...  
Vertex_handle  insert_in_facet (const Point &p, Cell_handle c, int i) 
As above, insertion in the facet (c,i) . More...  
Vertex_handle  insert_in_edge (const Point &p, const Edge &e) 
Inserts p in the edge e . More...  
Vertex_handle  insert_in_edge (const Point &p, Cell_handle c, int i, int j) 
As above, inserts p in the edge \( (i, j)\) of c . More...  
Vertex_handle  insert_outside_convex_hull (const Point &p, Cell_handle c) 
The cell c must be an infinite cell containing p . More...  
Vertex_handle  insert_outside_affine_hull (const Point &p) 
p is linked to all the points, and the infinite vertex is linked to all the points (including p ) to triangulate the new infinite face, so that all the points now belong to the boundary of the convex hull. More...  
template<class CellIt >  
Vertex_handle  insert_in_hole (const Point &p, CellIt cell_begin, CellIt cell_end, Cell_handle begin, int i) 
Creates a new vertex by starring a hole. More...  
template<class CellIt >  
Vertex_handle  insert_in_hole (const Point &p, CellIt cell_begin, CellIt cell_end, Cell_handle begin, int i, Vertex_handle newv) 
Same as above, except that newv will be used as the new vertex, which must have been allocated previously with e.g. create_vertex .  
Cell, Face, Edge and Vertex Iterators  
The following iterators allow the user to visit cells, facets, edges and vertices of the triangulation. These iterators are nonmutable, bidirectional and their value types are respectively  
Finite_vertices_iterator  finite_vertices_begin () const 
Starts at an arbitrary finite vertex. More...  
Finite_vertices_iterator  finite_vertices_end () const 
Pasttheend iterator.  
Finite_edges_iterator  finite_edges_begin () const 
Starts at an arbitrary finite edge. More...  
Finite_edges_iterator  finite_edges_end () const 
Pasttheend iterator.  
Finite_facets_iterator  finite_facets_begin () const 
Starts at an arbitrary finite facet. More...  
Finite_facets_iterator  finite_facets_end () const 
Pasttheend iterator.  
Finite_cells_iterator  finite_cells_begin () const 
Starts at an arbitrary finite cell. More...  
Finite_cells_iterator  finite_cells_end () const 
Pasttheend iterator.  
All_vertices_iterator  all_vertices_begin () const 
Starts at an arbitrary vertex. More...  
All_vertices_iterator  all_vertices_end () const 
Pasttheend iterator.  
All_edges_iterator  all_edges_begin () const 
Starts at an arbitrary edge. More...  
All_edges_iterator  all_edges_end () const 
Pasttheend iterator.  
All_facets_iterator  all_facets_begin () const 
Starts at an arbitrary facet. More...  
All_facets_iterator  all_facets_end () const 
Pasttheend iterator.  
All_cells_iterator  all_cells_begin () const 
Starts at an arbitrary cell. More...  
All_cells_iterator  all_cells_end () const 
Pasttheend iterator.  
Point_iterator  points_begin () const 
Iterates over the points of the triangulation.  
Point_iterator  points_end () const 
Pasttheend iterator.  
Ranges  
In order to write C++ 11 Note that vertex and cell ranges are special. See Section Iterators and Ranges in the User Manual.  
All_cell_handles  all_cell_handles () const 
returns a range of iterators over all cells (even the infinite cells). More...  
All_facets  all_facets () const 
returns a range of iterators starting at an arbitrary facet. More...  
All_edges  all_edges () const 
returns a range of iterators starting at an arbitrary edge. More...  
All_vertex_handles  all_vertex_handles () const 
returns a range of iterators over all vertices (even the infinite one). More...  
Finite_cell_handles  finite_cell_handles () const 
returns a range of iterators over finite cells. More...  
Finite_facets  finite_facets () const 
returns a range of iterators starting at an arbitrary facet. More...  
Finite_edges  finite_edges () const 
returns a range of iterators starting at an arbitrary edge. More...  
Finite_vertex_handles  finite_vertex_handles () const 
returns a range of iterators over finite vertices. More...  
Points  points () const 
returns a range of iterators over the points of finite vertices.  
Segment_traverser_cell_handles  segment_traverser_cell_handles () const 
returns a range of iterators over the cells intersected by a line segment  
Segment_traverser_simplices  segment_traverser_simplices () const 
returns a range of iterators over the simplices intersected by a line segment  
Segment Cell Iterator  
The triangulation defines an iterator that visits cells intersected by a line segment. Segment Cell Iterator iterates over a sequence of cells which union contains the segment The cells visited form a facetconnected region containing both source and target points of the line segment
Note that for categories 4 and 6, it is not predetermined which incident cells are visited. However, exactly two of the incident cells
Its  
Segment_cell_iterator  segment_traverser_cells_begin (Vertex_handle vs, Vertex_handle vt) const 
returns the iterator that allows to visit the cells intersected by the line segment [vs,vt] . More...  
Segment_cell_iterator  segment_traverser_cells_begin (const Point &ps, const Point &pt, Cell_handle hint=Cell_handle()) const 
returns the iterator that allows to visit the cells intersected by the line segment [ps, pt] . More...  
Segment_cell_iterator  segment_traverser_cells_end () const 
returns the pasttheend iterator over the intersected cells. More...  
Segment Simplex Iterator  
The triangulation defines an iterator that visits all the triangulation simplices (vertices, edges, facets and cells) intersected by a line segment. The iterator traverses a connected sequence of simplices  possibly of all dimensions  intersected by the line segment Each simplex falls within one or more of the following categories:
Its  
Segment_simplex_iterator  segment_traverser_simplices_begin (Vertex_handle vs, Vertex_handle vt) const 
returns the iterator that allows to visit the simplices intersected by the line segment [vs,vt] . More...  
Segment_simplex_iterator  segment_traverser_simplices_begin (const Point &ps, const Point &pt, Cell_handle hint=Cell_handle()) const 
returns the iterator that allows to visit the simplices intersected by the line segment [ps,pt] . More...  
Segment_simplex_iterator  segment_traverser_simplices_end () const 
returns the pasttheend iterator over the intersected simplices. More...  
Cell and Facet Circulators  
The following circulators respectively visit all cells or all facets incident to a given edge. They are nonmutable and bidirectional. They are invalidated by any modification of one of the cells traversed.  
Cell_circulator  incident_cells (Edge e) const 
Starts at an arbitrary cell incident to e . More...  
Cell_circulator  incident_cells (Cell_handle c, int i, int j) const 
As above for edge (i,j) of c .  
Cell_circulator  incident_cells (Edge e, Cell_handle start) const 
Starts at cell start . More...  
Cell_circulator  incident_cells (Cell_handle c, int i, int j, Cell_handle start) const 
As above for edge (i,j) of c .  
The following circulators on facets are defined only in dimension 3, though facets are defined also in dimension 2: there are only two facets sharing an edge in dimension 2.  
Facet_circulator  incident_facets (Edge e) const 
Starts at an arbitrary facet incident to e . More...  
Facet_circulator  incident_facets (Cell_handle c, int i, int j) const 
As above for edge (i,j) of c .  
Facet_circulator  incident_facets (Edge e, Facet start) const 
Starts at facet start . More...  
Facet_circulator  incident_facets (Edge e, Cell_handle start, int f) const 
Starts at facet of index f in start .  
Facet_circulator  incident_facets (Cell_handle c, int i, int j, Facet start) const 
As above for edge (i,j) of c .  
Facet_circulator  incident_facets (Cell_handle c, int i, int j, Cell_handle start, int f) const 
As above for edge (i,j) of c and facet (start,f) .  
Traversal of the Incident Cells, Facets and Edges, and the Adjacent Vertices of a Given Vertex  
template<class OutputIterator >  
OutputIterator  incident_cells (Vertex_handle v, OutputIterator cells) const 
Copies the Cell_handle s of all cells incident to v to the output iterator cells . More...  
bool  try_lock_and_get_incident_cells (Vertex_handle v, std::vector< Cell_handle > &cells) const 
Try to lock and copy the Cell_handle s of all cells incident to v into cells . More...  
template<class OutputIterator >  
OutputIterator  finite_incident_cells (Vertex_handle v, OutputIterator cells) const 
Copies the Cell_handle s of all finite cells incident to v to the output iterator cells . More...  
template<class OutputIterator >  
OutputIterator  incident_facets (Vertex_handle v, OutputIterator facets) const 
Copies all Facet s incident to v to the output iterator facets . More...  
template<class OutputIterator >  
OutputIterator  finite_incident_facets (Vertex_handle v, OutputIterator facets) const 
Copies all finite Facet s incident to v to the output iterator facets . More...  
template<class OutputIterator >  
OutputIterator  incident_edges (Vertex_handle v, OutputIterator edges) const 
Copies all Edge s incident to v to the output iterator edges . More...  
template<class OutputIterator >  
OutputIterator  finite_incident_edges (Vertex_handle v, OutputIterator edges) const 
Copies all finite Edge s incident to v to the output iterator edges . More...  
template<class OutputIterator >  
OutputIterator  adjacent_vertices (Vertex_handle v, OutputIterator vertices) const 
Copies the Vertex_handle s of all vertices adjacent to v to the output iterator vertices . More...  
template<class OutputIterator >  
OutputIterator  finite_adjacent_vertices (Vertex_handle v, OutputIterator vertices) const 
Copies the Vertex_handle s of all finite vertices adjacent to v to the output iterator vertices . More...  
size_type  degree (Vertex_handle v) const 
Returns the degree of a vertex, that is, the number of incident vertices. More...  
Traversal Between Adjacent Cells  
int  mirror_index (Cell_handle c, int i) const 
Returns the index of c in its \( i^{th}\) neighbor. More...  
Vertex_handle  mirror_vertex (Cell_handle c, int i) const 
Returns the vertex of the \( i^{th}\) neighbor of c that is opposite to c . More...  
Facet  mirror_facet (Facet f) const 
Returns the same facet seen from the other adjacent cell.  
Checking  
The responsibility of keeping a valid triangulation belongs to the user when using advanced operations allowing a direct manipulation of cells and vertices. We provide the user with the following methods to help debugging.  
bool  is_valid (bool verbose=false) const 
This is a function for debugging purpose. More...  
bool  is_valid (Cell_handle c, bool verbose=false) const 
This is a function for debugging purpose. More...  
I/O  
CGAL provides an interface to Geomview for a 3Dtriangulation, see Chapter Chapter_Geomview on #include <CGAL/IO/Triangulation_geomview_ostream_3.h> The information in the  
istream &  operator>> (istream &is, Triangulation_3 &t) 
Reads the underlying combinatorial triangulation from is by calling the corresponding input operator of the triangulation data structure class (note that the infinite vertex is numbered 0), and the noncombinatorial information by calling the corresponding input operators of the vertex and the cell classes (such as point coordinates), which are provided by overloading the stream operators of the vertex and cell types. More...  
ostream &  operator<< (ostream &os, const Triangulation_3 &t) 
Writes the triangulation t into os .  
template<typename Tr_src , typename ConvertVertex , typename ConvertCell >  
std::istream &  file_input (std::istream &is, ConvertVertex convert_vertex=ConvertVertex(), ConvertCell convert_cell=ConvertCell()) 
The triangulation streamed in is , of original type Tr_src , is written into the triangulation. More...  
Concurrency  
void  set_lock_data_structure (Lock_data_structure *lock_ds) const 
Set the pointer to the lock data structure.  
Additional Inherited Members  
Static Public Member Functions inherited from CGAL::Triangulation_utils_3  
static unsigned int  next_around_edge (unsigned int i, unsigned int j) 
static int  vertex_triple_index (const int i, const int j) 
static unsigned int  ccw (unsigned int i) 
static unsigned int  cw (unsigned int i) 
typedef unspecified_type CGAL::Triangulation_3< Traits, TDS, SLDS >::Segment_cell_iterator 
iterator over cells intersected by a line segment.
Segment_cell_iterator
implements the concept ForwardIterator
and is nonmutable. Its value type is Cell_handle
.
typedef unspecified_type CGAL::Triangulation_3< Traits, TDS, SLDS >::Segment_simplex_iterator 
iterator over simplices intersected by a line segment.
Segment_simplex_iterator
implements the concept ForwardIterator
and is nonmutable. Its value type is Triangulation_simplex_3
.
enum CGAL::Triangulation_3::Locate_type 
The enum Locate_type
is defined by Triangulation_3
to specify which case occurs when locating a point in the triangulation.
Enumerator  

VERTEX  
EDGE  
FACET  
CELL  
OUTSIDE_CONVEX_HULL  
OUTSIDE_AFFINE_HULL 
CGAL::Triangulation_3< Traits, TDS, SLDS >::Triangulation_3  (  const Geom_traits &  traits = Geom_traits() , 
Lock_data_structure *  lock_ds = nullptr 

) 
Introduces a triangulation t
having only one vertex which is the infinite vertex.
lock_ds
is an optional pointer to the lock data structure for parallel operations. It must be provided if concurrency is enabled.
CGAL::Triangulation_3< Traits, TDS, SLDS >::Triangulation_3  (  const Triangulation_3< Traits, TDS, SLDS > &  tr  ) 
Copy constructor.
All vertices and faces are duplicated. The pointer to the lock data structure is not copied. Thus, the copy won't be concurrencysafe as long as the user has not call Triangulation_3::set_lock_data_structure
.
OutputIterator CGAL::Triangulation_3< Traits, TDS, SLDS >::adjacent_vertices  (  Vertex_handle  v, 
OutputIterator  vertices  
)  const 
Copies the Vertex_handle
s of all vertices adjacent to v
to the output iterator vertices
.
If t.dimension() < 0
, then do nothing. Returns the resulting output iterator.
v != Vertex_handle()
, t.is_vertex(v)
. All_cell_handles CGAL::Triangulation_3< Traits, TDS, SLDS >::all_cell_handles  (  )  const 
returns a range of iterators over all cells (even the infinite cells).
Returns an empty range when t.number_of_cells() == 0
.
All_cells_iterator
is Cell
, the value type of All_cell_handles::iterator
is Cell_handle
. All_cells_iterator CGAL::Triangulation_3< Traits, TDS, SLDS >::all_cells_begin  (  )  const 
Starts at an arbitrary cell.
Iterates over all cells (even infinite ones). Returns cells_end()
when t.dimension() < 3
.
All_edges CGAL::Triangulation_3< Traits, TDS, SLDS >::all_edges  (  )  const 
returns a range of iterators starting at an arbitrary edge.
Returns an empty range when t.dimension() < 2
.
All_edges_iterator CGAL::Triangulation_3< Traits, TDS, SLDS >::all_edges_begin  (  )  const 
Starts at an arbitrary edge.
Iterates over all edges (even infinite ones). Returns edges_end()
when t.dimension() < 1
.
All_facets CGAL::Triangulation_3< Traits, TDS, SLDS >::all_facets  (  )  const 
returns a range of iterators starting at an arbitrary facet.
Returns an empty range when t.dimension() < 2
.
All_facets_iterator CGAL::Triangulation_3< Traits, TDS, SLDS >::all_facets_begin  (  )  const 
Starts at an arbitrary facet.
Iterates over all facets (even infinite ones). Returns facets_end()
when t.dimension() < 2
.
All_vertex_handles CGAL::Triangulation_3< Traits, TDS, SLDS >::all_vertex_handles  (  )  const 
returns a range of iterators over all vertices (even the infinite one).
All_vertices_iterator
is Vertex
, the value type of All_vertex_handles::iterator
is Vertex_handle
. All_vertices_iterator CGAL::Triangulation_3< Traits, TDS, SLDS >::all_vertices_begin  (  )  const 
Starts at an arbitrary vertex.
Iterates over all vertices (even the infinite one).
bool CGAL::Triangulation_3< Traits, TDS, SLDS >::are_equal  (  const Facet &  f, 
Cell_handle  n,  
int  j  
)  const 
For these three methods:
t.dimension() == 3
. size_type CGAL::Triangulation_3< Traits, TDS, SLDS >::degree  (  Vertex_handle  v  )  const 
Returns the degree of a vertex, that is, the number of incident vertices.
The infinite vertex is counted.
v != Vertex_handle()
, t.is_vertex(v)
. OutputIterator CGAL::Triangulation_3< Traits, TDS, SLDS >::finite_adjacent_vertices  (  Vertex_handle  v, 
OutputIterator  vertices  
)  const 
Copies the Vertex_handle
s of all finite vertices adjacent to v
to the output iterator vertices
.
If t.dimension() < 0
, then do nothing. Returns the resulting output iterator.
v != Vertex_handle()
, t.is_vertex(v)
. Finite_cell_handles CGAL::Triangulation_3< Traits, TDS, SLDS >::finite_cell_handles  (  )  const 
returns a range of iterators over finite cells.
Returns an empty range when t.number_of_cells() == 0
.
Finite_cells_iterator
is Cell
, the value type of Finite_cell_handles::iterator
is Cell_handle
. Finite_cells_iterator CGAL::Triangulation_3< Traits, TDS, SLDS >::finite_cells_begin  (  )  const 
Starts at an arbitrary finite cell.
Then ++
and 
will iterate over finite cells. Returns finite_cells_end()
when t.dimension() < 3
.
Finite_edges CGAL::Triangulation_3< Traits, TDS, SLDS >::finite_edges  (  )  const 
returns a range of iterators starting at an arbitrary edge.
Returns an empty range when t.dimension() < 2
.
Finite_edges_iterator CGAL::Triangulation_3< Traits, TDS, SLDS >::finite_edges_begin  (  )  const 
Starts at an arbitrary finite edge.
Then ++
and 
will iterate over finite edges.
Finite_facets CGAL::Triangulation_3< Traits, TDS, SLDS >::finite_facets  (  )  const 
returns a range of iterators starting at an arbitrary facet.
Returns an empty range when t.dimension() < 2
.
Finite_facets_iterator CGAL::Triangulation_3< Traits, TDS, SLDS >::finite_facets_begin  (  )  const 
Starts at an arbitrary finite facet.
Then ++
and 
will iterate over finite facets. Returns finite_facets_end()
when t.dimension() < 2
.
OutputIterator CGAL::Triangulation_3< Traits, TDS, SLDS >::finite_incident_cells  (  Vertex_handle  v, 
OutputIterator  cells  
)  const 
Copies the Cell_handle
s of all finite cells incident to v
to the output iterator cells
.
Returns the resulting output iterator.
t.dimension() == 3
, v != Vertex_handle()
, t.is_vertex(v)
. OutputIterator CGAL::Triangulation_3< Traits, TDS, SLDS >::finite_incident_edges  (  Vertex_handle  v, 
OutputIterator  edges  
)  const 
Copies all finite Edge
s incident to v
to the output iterator edges
.
Returns the resulting output iterator.
t.dimension() > 0
, v != Vertex_handle()
, t.is_vertex(v)
. OutputIterator CGAL::Triangulation_3< Traits, TDS, SLDS >::finite_incident_facets  (  Vertex_handle  v, 
OutputIterator  facets  
)  const 
Copies all finite Facet
s incident to v
to the output iterator facets
.
Returns the resulting output iterator.
t.dimension() > 1
, v != Vertex_handle()
, t.is_vertex(v)
. Finite_vertex_handles CGAL::Triangulation_3< Traits, TDS, SLDS >::finite_vertex_handles  (  )  const 
returns a range of iterators over finite vertices.
Finite_vertices_iterator
is Vertex
, the value type of Finite_vertex_handles::iterator
is Vertex_handle
. Finite_vertices_iterator CGAL::Triangulation_3< Traits, TDS, SLDS >::finite_vertices_begin  (  )  const 
Starts at an arbitrary finite vertex.
Then ++
and 
will iterate over finite vertices.
bool CGAL::Triangulation_3< Traits, TDS, SLDS >::flip  (  Cell_handle  c, 
int  i,  
int  j  
) 
Before flipping, these methods check that edge e=(c,i,j)
is flippable (which is quite expensive).
They return false
or true
according to this test.
bool CGAL::Triangulation_3< Traits, TDS, SLDS >::flip  (  Cell_handle  c, 
int  i  
) 
Before flipping, these methods check that facet f=(c,i)
is flippable (which is quite expensive).
They return false
or true
according to this test.
void CGAL::Triangulation_3< Traits, TDS, SLDS >::flip_flippable  (  Cell_handle  c, 
int  i,  
int  j  
) 
Should be preferred to the previous methods when the edge is known to be flippable.
void CGAL::Triangulation_3< Traits, TDS, SLDS >::flip_flippable  (  Cell_handle  c, 
int  i  
) 
Should be preferred to the previous methods when the facet is known to be flippable.
bool CGAL::Triangulation_3< Traits, TDS, SLDS >::has_vertex  (  const Facet &  f, 
Vertex_handle  v,  
int &  j  
)  const 
If v
is a vertex of f
, then j
is the index of v
in the cell f.first
, and the method returns true
.
t.dimension() == 3
bool CGAL::Triangulation_3< Traits, TDS, SLDS >::has_vertex  (  Cell_handle  c, 
int  i,  
Vertex_handle  v,  
int &  j  
)  const 
Same for facet (c,i)
.
Computes the index j
of v
in c
.
Cell_circulator CGAL::Triangulation_3< Traits, TDS, SLDS >::incident_cells  (  Edge  e  )  const 
Starts at an arbitrary cell incident to e
.
t.dimension() == 3
. Cell_circulator CGAL::Triangulation_3< Traits, TDS, SLDS >::incident_cells  (  Edge  e, 
Cell_handle  start  
)  const 
Starts at cell start
.
t.dimension() == 3
and start
is incident to e
. OutputIterator CGAL::Triangulation_3< Traits, TDS, SLDS >::incident_cells  (  Vertex_handle  v, 
OutputIterator  cells  
)  const 
Copies the Cell_handle
s of all cells incident to v
to the output iterator cells
.
Returns the resulting output iterator.
t.dimension() == 3
, v != Vertex_handle()
, t.is_vertex(v)
. OutputIterator CGAL::Triangulation_3< Traits, TDS, SLDS >::incident_edges  (  Vertex_handle  v, 
OutputIterator  edges  
)  const 
Copies all Edge
s incident to v
to the output iterator edges
.
Returns the resulting output iterator.
t.dimension() > 0
, v != Vertex_handle()
, t.is_vertex(v)
. Facet_circulator CGAL::Triangulation_3< Traits, TDS, SLDS >::incident_facets  (  Edge  e  )  const 
Starts at an arbitrary facet incident to e
.
t.dimension() == 3
Facet_circulator CGAL::Triangulation_3< Traits, TDS, SLDS >::incident_facets  (  Edge  e, 
Facet  start  
)  const 
Starts at facet start
.
start
is incident to e
. OutputIterator CGAL::Triangulation_3< Traits, TDS, SLDS >::incident_facets  (  Vertex_handle  v, 
OutputIterator  facets  
)  const 
Copies all Facet
s incident to v
to the output iterator facets
.
Returns the resulting output iterator.
t.dimension() > 1
, v != Vertex_handle()
, t.is_vertex(v)
. Cell_handle CGAL::Triangulation_3< Traits, TDS, SLDS >::inexact_locate  (  const Point &  query, 
Cell_handle  start = Cell_handle() 

)  const 
Same as locate()
but uses inexact predicates.
This function returns a handle on a cell that is a good approximation of the exact location of query
, while being faster. Note that it may return a handle on a cell whose interior does not contain query
. When the triangulation has dimension smaller than 3, start
is returned.
Note that this function is available only if the cartesian coordinates of query
are accessible with functions x()
, y()
and z()
.
Vertex_handle CGAL::Triangulation_3< Traits, TDS, SLDS >::insert  (  const Point &  p, 
Cell_handle  start = Cell_handle() 

) 
Inserts the point p
in the triangulation and returns the corresponding vertex.
If point p
coincides with an already existing vertex, this vertex is returned and the triangulation remains unchanged.
If point p
lies in the convex hull of the points, it is added naturally: if it lies inside a cell, the cell is split into four cells, if it lies on a facet, the two incident cells are split into three cells, if it lies on an edge, all the cells incident to this edge are split into two cells.
If point p
is strictly outside the convex hull but in the affine hull, p
is linked to all visible points on the convex hull to form the new triangulation. See Figure Triangulation3figinsert_outside_convex_hull.
If point p
is outside the affine hull of the points, p
is linked to all the points, and the dimension of the triangulation is incremented. All the points now belong to the boundary of the convex hull, so, the infinite vertex is linked to all the points to triangulate the new infinite face. See Figure Triangulation3figinsert_outside_affine_hull. The optional argument start
is used as a starting place for the search.
Vertex_handle CGAL::Triangulation_3< Traits, TDS, SLDS >::insert  (  const Point &  p, 
Locate_type  lt,  
Cell_handle  loc,  
int  li,  
int  lj  
) 
std::ptrdiff_t CGAL::Triangulation_3< Traits, TDS, SLDS >::insert  (  PointWithInfoInputIterator  first, 
PointWithInfoInputIterator  last  
) 
Inserts the points in the iterator range [first,last)
in the given order, and returns the number of inserted points.
Given a pair (p,i)
, the vertex v
storing p
also stores i
, that is v.point() == p
and v.info() == i
. If several pairs have the same point, only one vertex is created, and one of the objects of type Vertex::Info
will be stored in the vertex.
Vertex
must be model of the concept TriangulationVertexBaseWithInfo_3
.PointWithInfoInputIterator  must be an input iterator with the value type std::pair<Point,Vertex::Info> . 
Vertex_handle CGAL::Triangulation_3< Traits, TDS, SLDS >::insert_in_cell  (  const Point &  p, 
Cell_handle  c  
) 
Inserts the point p
in the cell c
.
The cell c
is split into 4 tetrahedra.
t.dimension() == 3
and p
lies strictly inside cell c
. Vertex_handle CGAL::Triangulation_3< Traits, TDS, SLDS >::insert_in_edge  (  const Point &  p, 
const Edge &  e  
) 
Inserts p
in the edge e
.
In dimension 3, all the cells having this edge are split into 2 tetrahedra; in dimension 2, the 2 neighboring facets are split into 2 triangles; in dimension 1, the edge is split into 2 edges.
t.dimension()
\( \geq1\) and p
lies on edge e
. Vertex_handle CGAL::Triangulation_3< Traits, TDS, SLDS >::insert_in_edge  (  const Point &  p, 
Cell_handle  c,  
int  i,  
int  j  
) 
As above, inserts p
in the edge \( (i, j)\) of c
.
Vertex_handle CGAL::Triangulation_3< Traits, TDS, SLDS >::insert_in_facet  (  const Point &  p, 
const Facet &  f  
) 
Inserts the point p
in the facet f
.
In dimension 3, the 2 neighboring cells are split into 3 tetrahedra; in dimension 2, the facet is split into 3 triangles.
t.dimension()
\( \geq2\) and p
lies strictly inside face f
. Vertex_handle CGAL::Triangulation_3< Traits, TDS, SLDS >::insert_in_facet  (  const Point &  p, 
Cell_handle  c,  
int  i  
) 
As above, insertion in the facet (c,i)
.
Vertex_handle CGAL::Triangulation_3< Traits, TDS, SLDS >::insert_in_hole  (  const Point &  p, 
CellIt  cell_begin,  
CellIt  cell_end,  
Cell_handle  begin,  
int  i  
) 
Creates a new vertex by starring a hole.
It takes an iterator range [cell_begin,cell_end)
of Cell_handle
s which specifies a hole: a set of connected cells (resp. facets in dimension 2) which is starshaped wrt p
. (begin
, i
) is a facet (resp. an edge) on the boundary of the hole, that is, begin
belongs to the set of cells (resp. facets) previously described, and begin>neighbor(i)
does not. Then this function deletes all the cells (resp. facets) describing the hole, creates a new vertex v
, and for each facet (resp. edge) on the boundary of the hole, creates a new cell (resp. facet) with v
as vertex. Then v>set_point(p)
is called and v
is returned.
This operation is equivalent to calling tds().insert_in_hole(cell_begin, cell_end, begin, i); v>set_point(p)
.
t.dimension()
\( \geq2\), the set of cells (resp. facets in dimension 2) is connected, its boundary is connected, and p
lies inside the hole, which is starshaped wrt p
. Vertex_handle CGAL::Triangulation_3< Traits, TDS, SLDS >::insert_outside_affine_hull  (  const Point &  p  ) 
p
is linked to all the points, and the infinite vertex is linked to all the points (including p
) to triangulate the new infinite face, so that all the points now belong to the boundary of the convex hull.
See Figure Triangulation3figinsert_outside_affine_hull.
This method can be used to insert the first point in an empty triangulation.
t.dimension() < 3
and p
lies outside the affine hull of the points.Vertex_handle CGAL::Triangulation_3< Traits, TDS, SLDS >::insert_outside_convex_hull  (  const Point &  p, 
Cell_handle  c  
) 
The cell c
must be an infinite cell containing p
.
Links p
to all points in the triangulation that are visible from p
. Updates consequently the infinite faces. See Figure Triangulation3figinsert_outside_convex_hull.
t.dimension() > 0
, c
, and the \( k\)face represented by c
is infinite and contains t
.bool CGAL::Triangulation_3< Traits, TDS, SLDS >::is_cell  (  Vertex_handle  u, 
Vertex_handle  v,  
Vertex_handle  w,  
Vertex_handle  x,  
Cell_handle &  c,  
int &  i,  
int &  j,  
int &  k,  
int &  l  
)  const 
Tests whether (u,v,w,x)
is a cell of t
.
If the cell c
is found, the method computes the indices i
, j
, k
and l
of the vertices u
, v
, w
and x
in c
, in this order.
u
, v
, w
and x
are vertices of t
. bool CGAL::Triangulation_3< Traits, TDS, SLDS >::is_cell  (  Vertex_handle  u, 
Vertex_handle  v,  
Vertex_handle  w,  
Vertex_handle  x,  
Cell_handle &  c  
)  const 
Tests whether (u,v,w,x)
is a cell of t
and computes this cell c
.
u
, v
, w
and x
are vertices of t
. bool CGAL::Triangulation_3< Traits, TDS, SLDS >::is_edge  (  Vertex_handle  u, 
Vertex_handle  v,  
Cell_handle &  c,  
int &  i,  
int &  j  
)  const 
Tests whether (u,v)
is an edge of t
.
If the edge is found, it gives a cell c
having this edge and the indices i
and j
of the vertices u
and v
in c
, in this order.
u
and v
are vertices of t
. bool CGAL::Triangulation_3< Traits, TDS, SLDS >::is_facet  (  Vertex_handle  u, 
Vertex_handle  v,  
Vertex_handle  w,  
Cell_handle &  c,  
int &  i,  
int &  j,  
int &  k  
)  const 
Tests whether (u,v,w)
is a facet of t
.
If the facet is found, it computes a cell c
having this facet and the indices i
, j
and k
of the vertices u
, v
and w
in c
, in this order.
u
, v
and w
are vertices of t
. bool CGAL::Triangulation_3< Traits, TDS, SLDS >::is_infinite  (  Cell_handle  c  )  const 
true
, iff c
is incident to the infinite vertex.
t.dimension() == 3
. bool CGAL::Triangulation_3< Traits, TDS, SLDS >::is_infinite  (  Cell_handle  c, 
int  i  
)  const 
true
, iff the facet i
of cell c
is incident to the infinite vertex.
t.dimension()
\( \geq2\) and \( i\in\{0,1,2,3\}\) in dimension 3, \( i=3\) in dimension 2. bool CGAL::Triangulation_3< Traits, TDS, SLDS >::is_infinite  (  const Facet &  f  )  const 
true
iff facet f
is incident to the infinite vertex.
t.dimension()
\( \geq2\). bool CGAL::Triangulation_3< Traits, TDS, SLDS >::is_infinite  (  Cell_handle  c, 
int  i,  
int  j  
)  const 
true
, iff the edge (i,j)
of cell c
is incident to the infinite vertex.
t.dimension()
\( \geq1\) and \( i\neq j\). Moreover \( i,j \in\{0,1,2,3\}\) in dimension 3, \( i,j \in\{0,1,2\}\) in dimension 2, \( i,j \in\{0,1\}\) in dimension 1. bool CGAL::Triangulation_3< Traits, TDS, SLDS >::is_infinite  (  const Edge &  e  )  const 
true
iff edge e
is incident to the infinite vertex.
t.dimension()
\( \geq1\). bool CGAL::Triangulation_3< Traits, TDS, SLDS >::is_valid  (  bool  verbose = false  )  const 
This is a function for debugging purpose.
Checks the combinatorial validity of the triangulation. Checks also the validity of its geometric embedding (see Section Representation). When verbose
is set to true
, messages describing the first invalidity encountered are printed.
bool CGAL::Triangulation_3< Traits, TDS, SLDS >::is_valid  (  Cell_handle  c, 
bool  verbose = false 

)  const 
This is a function for debugging purpose.
Checks the combinatorial validity of the cell by calling the is_valid
method of the cell class. Also checks the geometric validity of c
, if c
is finite. (See Section Representation.)
When verbose
is set to true
, messages are printed to give a precise indication of the kind of invalidity encountered.
bool CGAL::Triangulation_3< Traits, TDS, SLDS >::is_vertex  (  const Point &  p, 
Vertex_handle &  v  
)  const 
Tests whether p
is a vertex of t
by locating p
in the triangulation.
If p
is found, the associated vertex v
is given.
Cell_handle CGAL::Triangulation_3< Traits, TDS, SLDS >::locate  (  const Point &  query, 
Cell_handle  start = Cell_handle() , 

bool *  could_lock_zone = nullptr 

)  const 
If the point query
lies inside the convex hull of the points, the cell that contains the query in its interior is returned.
If query
lies on a facet, an edge or on a vertex, one of the cells having query
on its boundary is returned.
If the point query
lies outside the convex hull of the points, an infinite cell with vertices \( \{ p, q, r, \infty\}\) is returned such that the tetrahedron \( ( p, q, r, query )\) is positively oriented (the rest of the triangulation lies on the other side of facet \( ( p, q, r )\)).
Note that locate works even in degenerate dimensions: in dimension 2 (resp. 1, 0) the Cell_handle
returned is the one that represents the facet (resp. edge, vertex) containing the query point.
The optional argument start
is used as a starting place for the search.
The optional argument could_lock_zone
is used by the concurrencysafe version of the triangulation. When the pointer is not null, the locate will try to lock all the cells along the walk. If it succeeds, *could_lock_zone
is true
, otherwise it is false. In any case, the locked cells are not unlocked by locate
, leaving this choice to the user.
Cell_handle CGAL::Triangulation_3< Traits, TDS, SLDS >::locate  (  const Point &  query, 
Locate_type &  lt,  
int &  li,  
int &  lj,  
Cell_handle  start = Cell_handle() , 

bool *  could_lock_zone = nullptr 

)  const 
If query
lies inside the affine hull of the points, the \( k\)face (finite or infinite) that contains query
in its interior is returned, by means of the cell returned together with lt
, which is set to the locate type of the query (VERTEX, EDGE, FACET, CELL
, or OUTSIDE_CONVEX_HULL
if the cell is infinite and query
lies strictly in it) and two indices li
and lj
that specify the \( k\)face of the cell containing query
.
If the \( k\)face is a cell, li
and lj
have no meaning; if it is a facet (resp. vertex), li
gives the index of the facet (resp. vertex) and lj
has no meaning; if it is and edge, li
and lj
give the indices of its vertices.
If the point query
lies outside the affine hull of the points, which can happen in case of degenerate dimensions, lt
is set to OUTSIDE_AFFINE_HULL
, and the cell returned has no meaning. As a particular case, if there is no finite vertex yet in the triangulation, lt
is set to OUTSIDE_AFFINE_HULL
and locate returns the default constructed handle.
The optional argument start
is used as a starting place for the search.
The optional argument could_lock_zone
is used by the concurrencysafe version of the triangulation. When the pointer is not null, the locate will try to lock all the cells along the walk. If it succeeds, *could_lock_zone
is true
, otherwise it is false. In any case, the locked cells are not unlocked by locate
, leaving this choice to the user.
int CGAL::Triangulation_3< Traits, TDS, SLDS >::mirror_index  (  Cell_handle  c, 
int  i  
)  const 
Returns the index of c
in its \( i^{th}\) neighbor.
Vertex_handle CGAL::Triangulation_3< Traits, TDS, SLDS >::mirror_vertex  (  Cell_handle  c, 
int  i  
)  const 
Returns the vertex of the \( i^{th}\) neighbor of c
that is opposite to c
.
size_type CGAL::Triangulation_3< Traits, TDS, SLDS >::number_of_edges  (  )  const 
The number of edges.
Returns 0 if t.dimension() < 1
.
size_type CGAL::Triangulation_3< Traits, TDS, SLDS >::number_of_facets  (  )  const 
The number of facets.
Returns 0 if t.dimension() < 2
.
size_type CGAL::Triangulation_3< Traits, TDS, SLDS >::number_of_finite_cells  (  )  const 
The number of finite cells.
Returns 0 if t.dimension() < 3
.
size_type CGAL::Triangulation_3< Traits, TDS, SLDS >::number_of_finite_edges  (  )  const 
The number of finite edges.
Returns 0 if t.dimension() < 1
.
size_type CGAL::Triangulation_3< Traits, TDS, SLDS >::number_of_finite_facets  (  )  const 
The number of finite facets.
Returns 0 if t.dimension() < 2
.
Triangulation_3& CGAL::Triangulation_3< Traits, TDS, SLDS >::operator=  (  const Triangulation_3< Traits, TDS, SLDS > &  tr  ) 
The triangulation tr
is duplicated, and modifying the copy after the duplication does not modify the original.
The previous triangulation held by t
is deleted.
bool CGAL::Triangulation_3< Traits, TDS, SLDS >::operator==  (  const Triangulation_3< GT, Tds1 > &  t1, 
const Triangulation_3< GT, Tds2 > &  t2  
) 
Equality operator.
Returns true
iff there exist a bijection between the vertices of t1
and those of t2
and a bijection between the cells of t1
and those of t2
, which preserve the geometry of the triangulation, that is, the points of each corresponding pair of vertices are equal, and the tetrahedra corresponding to each pair of cells are equal (up to a permutation of their vertices).
const Point& CGAL::Triangulation_3< Traits, TDS, SLDS >::point  (  Cell_handle  c, 
int  i  
)  const 
Returns the point given by vertex i
of cell c
.
t.dimension()
\( \geq0\) and \( i \in\{0,1,2,3\}\) in dimension 3, \( i \in\{0,1,2\}\) in dimension 2, \( i \in\{0,1\}\) in dimension 1, \( i = 0\) in dimension 0, and the vertex is finite. const Point& CGAL::Triangulation_3< Traits, TDS, SLDS >::point  (  Vertex_handle  v  )  const 
Same as the previous method for vertex v
.
t.dimension()
\( \geq0\) and the vertex is finite. Segment CGAL::Triangulation_3< Traits, TDS, SLDS >::segment  (  const Edge &  e  )  const 
Returns the line segment formed by the vertices of e
.
t.dimension()
\( \geq1\) and e
is finite. Segment CGAL::Triangulation_3< Traits, TDS, SLDS >::segment  (  Cell_handle  c, 
int  i,  
int  j  
)  const 
Same as the previous method for edge (c,i,j)
.
Segment_cell_iterator CGAL::Triangulation_3< Traits, TDS, SLDS >::segment_traverser_cells_begin  (  Vertex_handle  vs, 
Vertex_handle  vt  
)  const 
returns the iterator that allows to visit the cells intersected by the line segment [vs,vt]
.
The initial value of the iterator is the cell containing vs
and intersected by the line segment [vs,vt]
in its interior.
The first cell incident to vt
is the last valid value of the iterator. It is followed by segment_traverser_cells_end()
.
vs
and vt
must be different vertices and neither can be the infinite vertex. triangulation.dimension() >= 2
Segment_cell_iterator CGAL::Triangulation_3< Traits, TDS, SLDS >::segment_traverser_cells_begin  (  const Point &  ps, 
const Point &  pt,  
Cell_handle  hint = Cell_handle() 

)  const 
returns the iterator that allows to visit the cells intersected by the line segment [ps, pt]
.
If [ps,pt]
entirely lies outside the convex hull, the iterator visits exactly one infinite cell.
The initial value of the iterator is the cell containing ps
. If more than one cell contains ps
(e.g. if ps
lies on a vertex), the initial value is the cell intersected by the interior of the line segment [ps,pt]
. If ps
lies outside the convex hull and pt
inside the convex full, the initial value is the infinite cell which finite facet is intersected by the interior of [ps,pt]
.
The first cell containing pt
is the last valid value of the iterator. It is followed by segment_traverser_cells_end()
.
The optional argument hint
can reduce the time to construct the iterator if it is geometrically close to ps
.
ps
and pt
must be different points. triangulation.dimension() >= 2
. If the dimension is 2, both ps
and pt
must lie in the affine hull. Segment_cell_iterator CGAL::Triangulation_3< Traits, TDS, SLDS >::segment_traverser_cells_end  (  )  const 
returns the pasttheend iterator over the intersected cells.
This iterator cannot be dereferenced. It indicates when the Segment_cell_iterator
has passed the target.
triangulation.dimension() >= 2
Segment_simplex_iterator CGAL::Triangulation_3< Traits, TDS, SLDS >::segment_traverser_simplices_begin  (  Vertex_handle  vs, 
Vertex_handle  vt  
)  const 
returns the iterator that allows to visit the simplices intersected by the line segment [vs,vt]
.
The initial value of the iterator is vs
. The iterator remains valid until vt
is passed.
vs
and vt
must be different vertices and neither can be the infinite vertex. triangulation.dimension() >= 2
Segment_simplex_iterator CGAL::Triangulation_3< Traits, TDS, SLDS >::segment_traverser_simplices_begin  (  const Point &  ps, 
const Point &  pt,  
Cell_handle  hint = Cell_handle() 

)  const 
returns the iterator that allows to visit the simplices intersected by the line segment [ps,pt]
.
If [ps,pt]
entirely lies outside the convex hull, the iterator visits exactly one infinite cell.
The initial value of the iterator is the lowest dimension simplex containing ps
.
The iterator remains valid until the first simplex containing pt
is passed.
The optional argument hint
can reduce the time to construct the iterator if it is close to ps
.
ps
and pt
must be different points. triangulation.dimension() >= 2
. If the dimension is 2, both ps
and pt
must lie in the affine hull. Segment_simplex_iterator CGAL::Triangulation_3< Traits, TDS, SLDS >::segment_traverser_simplices_end  (  )  const 
returns the pasttheend iterator over the intersected simplices.
This iterator cannot be dereferenced. It indicates when the Segment_simplex_iterator
has passed the target.
triangulation.dimension() >= 2
void CGAL::Triangulation_3< Traits, TDS, SLDS >::set_infinite_vertex  (  Vertex_handle  v  ) 
This is an advanced function.
This method is meant to be used only if you have done a lowlevel operation on the underlying tds that invalidated the infinite vertex. Sets the infinite vertex.
Bounded_side CGAL::Triangulation_3< Traits, TDS, SLDS >::side_of_cell  (  const Point &  p, 
Cell_handle  c,  
Locate_type &  lt,  
int &  li,  
int &  lj  
)  const 
Returns a value indicating on which side of the oriented boundary of c
the point p
lies.
More precisely, it returns:
ON_BOUNDED_SIDE
if p
is inside the cell. For an infinite cell this means that p
lies strictly in the half space limited by its finite facet and not containing any other point of the triangulation.ON_BOUNDARY
if p on the boundary of the cell. For an infinite cell this means that p
lies on the finite facet. Then lt
together with li
and lj
give the precise location on the boundary. (See the descriptions of the locate methods.)ON_UNBOUNDED_SIDE
if p
lies outside the cell. For an infinite cell this means that p
does not satisfy either of the two previous conditions. t.dimension() == 3
Bounded_side CGAL::Triangulation_3< Traits, TDS, SLDS >::side_of_edge  (  const Point &  p, 
const Edge &  e,  
Locate_type &  lt,  
int &  li  
)  const 
Returns a value indicating on which side of the oriented boundary of e
the point p
lies:
ON_BOUNDED_SIDE
if p
is inside the edge. For an infinite edge this means that p
lies in the half line defined by the vertex and not containing any other point of the triangulation.ON_BOUNDARY
if p
equals one of the vertices, li
give the index of the vertex in the cell storing e
ON_UNBOUNDED_SIDE
if p
lies outside the edge. For an infinite edge this means that p
lies on the other half line, which contains the other points of the triangulation. t.dimension() == 1
and p
is collinear with the points of the triangulation. e.second == 0
and e.third
\( =1\) (in dimension 1 there is only one edge per cell). Bounded_side CGAL::Triangulation_3< Traits, TDS, SLDS >::side_of_facet  (  const Point &  p, 
const Facet &  f,  
Locate_type &  lt,  
int &  li,  
int &  lj  
)  const 
Returns a value indicating on which side of the oriented boundary of f
the point p
lies:
ON_BOUNDED_SIDE
if p
is inside the facet. For an infinite facet this means that p
lies strictly in the half plane limited by its finite edge and not containing any other point of the triangulation .ON_BOUNDARY
if p
is on the boundary of the facet. For an infinite facet this means that p
lies on the finite edge. lt
, li
and lj
give the precise location of p
on the boundary of the facet. li
and lj
refer to indices in the degenerate cell c
representing f
.ON_UNBOUNDED_SIDE
if p
lies outside the facet. For an infinite facet this means that p
does not satisfy either of the two previous conditions.t.dimension() == 2
and p
lies in the plane containing the triangulation. f.second
\( =3\) (in dimension 2 there is only one facet per cell). void CGAL::Triangulation_3< Traits, TDS, SLDS >::swap  (  Triangulation_3< Traits, TDS, SLDS > &  tr  ) 
The triangulations tr
and t
are swapped.
t.swap(tr)
should be preferred to t = tr
or to t(tr)
if tr
is deleted after that. Indeed, there is no copy of cells and vertices, thus this method runs in constant time.
Triangulation_data_structure& CGAL::Triangulation_3< Traits, TDS, SLDS >::tds  (  ) 
Returns a reference to the triangulation data structure.
This method is mainly a help for users implementing their own triangulation algorithms. The responsibility of keeping a valid triangulation belongs to the user when using advanced operations allowing a direct manipulation of the tds
.
Tetrahedron CGAL::Triangulation_3< Traits, TDS, SLDS >::tetrahedron  (  Cell_handle  c  )  const 
Returns the tetrahedron formed by the four vertices of c
.
t.dimension() == 3
and the cell is finite. Triangle CGAL::Triangulation_3< Traits, TDS, SLDS >::triangle  (  Cell_handle  c, 
int  i  
)  const 
Returns the triangle formed by the three vertices of facet (c,i)
.
The triangle is oriented so that its normal points to the inside of cell c
.
t.dimension()
\( \geq2\) and \( i \in\{0,1,2,3\}\) in dimension 3, \( i = 3\) in dimension 2, and the facet is finite. Triangle CGAL::Triangulation_3< Traits, TDS, SLDS >::triangle  (  const Facet &  f  )  const 
Same as the previous method for facet f
.
t.dimension()
\( \geq2\) and the facet is finite. bool CGAL::Triangulation_3< Traits, TDS, SLDS >::try_lock_and_get_incident_cells  (  Vertex_handle  v, 
std::vector< Cell_handle > &  cells  
)  const 
Try to lock and copy the Cell_handle
s of all cells incident to v
into cells
.
Returns true
in case of success. Otherwise, cells
is emptied and the function returns false. In any case, the locked cells are not unlocked by try_lock_and_get_incident_cells()
, leaving this choice to the user.
t.dimension() == 3
, v != Vertex_handle()
, t.is_vertex(v)
.